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Abstract Detail


Ecological Section

Hawkins, Tracy [1], Thornton, Rory [2].

The influence of temperature and winter flooding on the seed ecology of Quercus pagoda Raf.

Bottomland hardwood forests in the southeastern United States are characterized by seasonal flooding, and natural or anthropogenic disturbances may produce canopy gaps that result in wide variations in soil temperatures throughout the forested site. Although Quercus species commonly occur in these forests, rigorous studies of the influences of temperatures and long-term flooding on the seed (acorn) ecology of bottomland Quercus species is scant. In light of this, we investigated the effects of temperature and winter flooding on dormancy break and germination of acorns of Quercus pagoda (cherrybark oak), an ecologically and economically important red oak species of bottomland hardwood forests. Mature acorns harvested directly from Q. pagoda trees received 2, 4, 6, 8, 12, and 18 weeks of cold stratification (5/1 ºC). Following 12 weeks of cold stratification, 80, 95, 99, and 96% of acorns germinated in light at incubation temperatures of 15/6 º, 20/10 º, 25/15 º, and 30/20 ºC, respectively. At 18 weeks of cold stratification, 52% of acorns had germinated and an additional 45% germinated within 96 hours after being moved to the four incubation temperatures. Cumulative germination for acorns submerged in a green tree reservoir (GTR) for 4, 6, 8, and 12 weeks (November through February), and then placed in the four incubation temperatures were comparable to those of acorns receiving these same periods of cold stratification. Acorns did not germinate while submerged. Quercus pagoda acorns require no more than 12 weeks of cold stratification for dormancy break and have nondeep physiological dormancy. Acorns are flood tolerant up to a period of at least 12 weeks during winter flooding, and submergence is as effective as cold stratification in breaking seed dormancy. These traits are well-suited to temperatures and hydrologic regimes associated with bottomland forests and some GTRs, and thus absence of seedling regeneration on these sites may be more attributable to post-germination requirements.

Broader Impacts:


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1 - USDA - Forest Service, Box 9681, Mississippi State, MS, 39762, USA
2 - USDA Forest Service, Box 9681, Mississippi State, MS, 39761, USA

Keywords:
red oak
cherrybark oak
Quercus
bottomland hardwoods
seed germination
seed dormancy break.

Presentation Type: Oral Paper:Papers for Sections
Session: 36
Location: Union B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 3:00 PM
Number: 36007
Abstract ID:392


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